Annular-shaped pipe connecting pieces made of metal function to attach to counter flanges of the pipe ends. The annular-shaped pipe connecting pieces engage behind the end flanges of the pipe connecting unit.
These compensators are utilized in pipelines subjected to thermal load for taking up expansions. Compensators are also used for attenuating vibrations and noise of equipment to be connected such as motors, pumps and the like. Likewise, building in rubber compensators is recommended to effectively interrupt the transmission of structure-borne noise and water-borne noise. Finally, a compensation of assembly inaccuracies can be undertaken with these compensators.
The most varied types of connecting units are known for pipelines. These connecting units each include an elastic, wave-shaped or hose-shaped bellows having connecting pieces incorporated at the ends thereof.
The compensator is preferably stiffened at its end flanges by annular-shaped inserts so that the bellows do not get torn out of the flange connection by the tension and compressive loads occurring during operation.
As a counter flange, standard welding neck flanges having a sealing bead are used which join at the end face to the pipeline. These welding neck flanges are, for example, in accordance with DIN 2633 (German Industrial Standard 2633). As a rule, additional seals when building in the rubber compensator are not required.
The elastomeric material of the rubber bellows is relatively sensitive to the formation of notches. For this reason, the sealing surfaces of the counter flanges must perforce be planar and offer a contact engaging surface for the entire seal surface of the compensator (see FIG. 4a herein). Flange embodiments having tongue and groove or flanges, which do not engage on the full surface, lead, in a short time, to fissure formations in the sealing surface and therefore to a failure of the rubber body.
FIGS. 4a to 4e herein show various examples for attaching compensators known per se. Thus, FIG. 4a shows a so-called slip-on flange (for example, DIN 28031) as a counter flange. This flange is soldered on the outside to the pipe end to be connected or is welded thereto. The sharp inner edge of the pipeline generates a notch in the rubber sealing surface. Notches of this kind ultimately lead to a destruction of the bellows under compression and tension loading.
The embodiment shown in FIG. 4b is of a slip-on flange. In this embodiment, a rough pipe end can cause damage to the rubber sealing surface. FIG. 4c shows a counter flange having an inner diameter which is too large. Such flanges can also damage the rubber sealing surface.
FIG. 4d shows a connection wherein the counter flange is configured as a so-called welding-neck flange. This does provide a problem-free seal-tight attachment but welding-neck flanges are expensive to manufacture.
A flat seal 30 can be additionally used as shown in FIG. 4e when there is a danger of damage with the embodiments shown in FIGS. 4a to 4c. However, this is an additional part and therefore constitutes an additional cost factor and makes assembly of the compensator in the pipeline more difficult. The problem of damage (see FIGS. 4a, 4b or 4c) is more likely to occur when such a flat seal is inadvertently omitted.
The compensator is intended to function together with welded-on flanges as a counter flange without additional seals or corresponding preparation of the joining location.